Linear multi-cylinder stirling cycle machine

ABSTRACT

An improved method and system for removing blockage from hydrocarbon transfer conduits ( 108 ). An apparatus and methods for cleaning a hydrocarbon transfer conduit is disclosed whereby a laser head ( 104 ) is placed in a hydrocarbon transfer conduit to be cleaned and supplied with a laser beam. The laser head applies the laser beam to an area in the hydrocarbon transfer conduit to be cleaned.

BACKGROUND

Oil and its byproducts play a major role in today's industries. Oil istypically removed from wells and transported through pipelines.Depending on the location of a well and the desired destination of theoil, such pipelines may be on the ground or at the sub-sea level.

The flow of oil through a pipeline can lead to the build up of differentsubstances which tend to impede the fluid flow. For instance, there maybe a buildup of scale, paraffin wax, gas hydrates, debris or sand in thepipeline as the oil flows through it. Depending on the nature of thefluid flowing through the pipeline and other surrounding circumstances,one or more of the above deposits may build up in a pipeline.

The scale causing blockage results from the precipitation of chemicalsfrom the brine found in the formation. Furthermore, a reservoir maycontain hydrogen sulfide (H₂S) gas, a sulfur-containing chemical may beused during the completion of the wells, or a formation water maycontain sulfide ion. In such instances, zinc sulfide (ZnS) or ironsulfide (FeS, Fe₂S₃, FeS₂) scales can form when a zinc bromide brine isexposed to the sulfide ion and where soluble iron exists as a result ofcorrosion. In addition, there might be sulfates of barium and strontiumdeposited, when a formation containing barium and strontium ions andinjected with sea water, is produced.

Typically, an acid treatment is performed to remove zinc sulfide, ironsulfide and other such scales. In contrast, barium sulfate and strontiumsulfate may be removed using alkaline solutions of chelating agents. Ineither case, a large amount of acids and/or other chemicals is passedthrough the pipe to be de-scaled to remove the deposits from the insideof the pipeline and allow the passage of fluids there through. However,this method of de-scaling has several disadvantages. One disadvantage ofthe current de-scaling methods is the need to handle and transport largeamounts of corrosive and often hazardous chemicals which are used tode-scale the pipeline. The risks associated with such chemicals isfurther magnified by the high temperature and pressures in the gas wellsand pipelines through which the chemicals are pumped.

Another disadvantage of the current de-scaling methods is that largevolumes of chemicals would often have to be passed through a pipeline tobe de-scaled. As a result, the process is both time consuming andexpensive to carry out. Yet another drawback of the current de-scalingmethods is the low efficiency of the de-scaling chemicals when used toclear particularly hard scales such as barium sulfate. This problem isparticularly aggravated by the fact that subsea pipelines are typicallyin cold environments which lower the efficiency of scale dissolution.Additionally, the use of such chemicals which need to be disposed afterpassage through the pipeline poses significant health, safety andenvironmental concerns.

Moreover, crude oil contains many different hydrocarbons includingparaffin wax. Consequently, paraffin wax depositions often occur whencrude oil or other hydrocarbons are produced or transported. Likescales, the formation of paraffin wax obstructs the fluid flow throughthe pipeline, thereby interfering with production and transportation ofhydrocarbons.

One method to prevent the formation of paraffin deposits is to heat thepipelines. However, this method is very expensive and is not feasiblefor sub-sea pipelines submerged in the cold sea water. Another methodfor removing the paraffin built up in a pipeline involves “pigging”,whereby a mechanical device is passed through the pipeline which scrapesthe inner wall of the pipeline and pushes the paraffin deposits through.One disadvantage of this method is that it is not effective in dealingwith a heavy paraffin build up. Specifically, when there is a heavyparaffin build up, as the mechanical device moves, at some point thecollection of the dislodged paraffin in front of the device prevents thedevice from going any further. This will result in a blockage of thepipeline which cannot be remedied by the mechanical device.

Another method for removing paraffin deposits is “hot oiling”. In “hotoiling”, a heated oil is pumped through the pipeline in order to removethe paraffin wax deposits. One drawback of this method is that largevolumes of hot oil must be passed through the pipeline making theprocess expensive. Moreover, this method is not well-suited for removalof deposits from long pipelines, pipelines under water or in other coldconditions. Specifically, as the oil moves through the pipe the heatwill dissipate and the oil fails to effectively remove the paraffindeposits. Additionally, the disposal of the hot oil poses significanthealth, safety and environmental concerns.

In some instances hot water, instead of hot oil, is pumped through thepipeline to remove the paraffin wax deposits. One disadvantage of thismethod is the formation of undesirable oil/water emulsions resultingfrom water's inability to dissolve or dilute the paraffin wax. Moreover,using hot water can contribute to the corrosion of the metal pipelines.

Another cause of blockage in pipelines is the formation of gas hydrateswhere an aqueous phase is inherently present, during the transportationof oil or gases. This is a common problem, especially in regions withlow temperatures, during winter season or at the sub-sea level. The lowtemperatures under such circumstances and the inevitable presence ofco-produced water lead to formation of gas hydrates in the pipelines.

One current method of dealing with such gas hydrates is to insulate thepipelines. However such an approach is very expensive. Another method isto pump methanol through the pipeline or use chemical methods such asaddition of anti-agglomerates (e.g. kinetic inhibitors or thermodynamicinhibitors). However, to be effective, large quantities of thesechemicals must be used making the process expensive. Moreover, theseanti-freeze substances are highly flammable adding a safety risk.

As discussed above, many of the current methods of removing unwanteddeposits from the pipelines depend upon the existence of a continuouscommunication through the pipeline. However, as various deposits buildup on the pipeline walls the opening for fluid flow becomes smaller andfluid flow may even be completely blocked. Under these circumstances theuse of fluids to clean the unwanted deposits becomes highly ineffective.Additionally, parts of the deposits on the pipeline walls may break offcausing a blockage of the pipeline. However, the current methods ofcleaning the pipeline walls are not well suited for dealing withpipeline blockages. As a result, the blockage may result in a pipelineshut down which can be very expensive for a pipeline operator.

Finally, information about the conditions inside a pipeline can be ofgreat value to an operator. For instance, the operator is ofteninterested to know about the nature and location of deposits formed onthe pipeline walls as well as the presence of cracks and otherdeformities in the pipeline.

FIGURES

Some specific example embodiments of the disclosure may be understood byreferring, in part, to the following description and the accompanyingdrawings.

FIG. 1 depicts a laser assisted cleaning apparatus in accordance with anexemplary embodiment of the present invention.

While embodiments of this disclosure have been depicted and describedand are defined by reference to example embodiments of the disclosure,such references do not imply a limitation on the disclosure, and no suchlimitation is to be inferred. The subject matter disclosed is capable ofconsiderable modification, alteration, and equivalents in form andfunction, as will occur to those skilled in the pertinent art and havingthe benefit of this disclosure. The depicted and described embodimentsof this disclosure are examples only, and not exhaustive of the scope ofthe disclosure.

SUMMARY

The present invention is directed to a conduit cleaning method andsystem. Specifically, the present invention is directed to an improvedmethod and system for removing blockage from hydrocarbon transferconduits.

In one exemplary embodiment, the present invention is directed to amethod of removing deposits from a hydrocarbon transfer conduitcomprising the steps of: placing a laser head in a hydrocarbon transferconduit to be cleaned; supplying the laser head with a laser beam; and,applying the laser beam from the laser head to an area in thehydrocarbon transfer conduit to be cleaned.

In another embodiment, the present invention is directed to a method ofremoving deposits from a pipe comprising the steps of: placing a heatsource in a pipe to be cleaned; placing a liquid in the pipe to becleaned; supplying the heat source with power; and, applying the powerfrom the heat source to the liquid in an area in the pipe to be cleaned.

In yet another embodiment, the present invention is directed to ahydrocarbon transfer conduit cleaning apparatus comprising: a laserhead; a laser source; and, an optical fiber communicatively coupling thelaser head and the laser source; wherein the laser head is placed in ahydrocarbon transfer conduit to be cleaned.

The features and advantages of the present disclosure will be readilyapparent to those skilled in the art upon a reading of the descriptionof exemplary embodiments, which follows.

DESCRIPTION

The present invention is directed to a conduit cleaning method andsystem. Specifically, the present invention is directed to an improvedmethod and system for removing blockage from hydrocarbon transferconduits.

As would be appreciated by those of ordinary skill in the art,hydrocarbons include a variety of naturally occurring organic compoundsof carbon and hydrogen, including, but not limited to, oil and naturalgas. Hydrocarbons and other fluids may be transferred through conduitswhich are pipes or channels used to carry fluids. For example, atransfer conduit may be a pipeline. As would be appreciated by those ofordinary skill in the art, a pipeline may be a pipe or a system of pipesdesigned to carry something such as oil, natural gas, or otherhydrocarbons, typically over long distances, above or under the ground.Referring now to FIG. 1, a laser assisted cleaning apparatus inaccordance with an exemplary embodiment of the present invention isdepicted generally with reference numeral 100. A laser source 102generates laser beams which are transferred to a laser head 104 throughan optical fiber 106 or any other suitable means for transferring thelaser beams. As would be appreciated by those of ordinary skill in theart, with the benefit of this disclosure, the optical fiber 106 may beenclosed in a coiled tubing or an umbilical, similar to that used tohold electrical cables, and kept in a reel. Extremely high power lasersources appropriate for this application are available from IPGPhotonics, Inc. of Oxford, Mass. Considering the availability of suchhigh power laser sources, there remains sufficient energy for scaleremoval even after accounting for the attenuation in the optical fibers106. In one exemplary embodiment, the optical fibers 106 may be part ofan umbilical that supplies power used to move the laser head 104 throughthe pipeline 108. As would be appreciated by those of ordinary skill inthe art, with the benefit of this disclosure, the umbilical may includea number of components including, but not limited to, optical fibers,electrical wires and one or more hydraulic lines which may be used todeliver a variety of materials to a desired location in the pipe.

The laser source 102 is placed outside the pipeline 108 on anappropriate platform and is optically coupled to the laser head 104. Asa result, the laser beam generated by the laser source 102 can betransferred to any desired location in the pipeline 108 using the laserhead 104. The laser head 104 will in turn apply the laser beam to thepipeline 108 walls. In one embodiment, the laser head 104 is alsooperable to direct the laser towards the front and the back of the laserhead 104. Accordingly, the laser assisted cleaning apparatus 100 may beused to clear the scales 112 formed on the pipeline 108 walls as well asany scales formed at any portion of the pipeline 108 cross section.

As would be appreciated by those of ordinary skill in the art, with thebenefit of this disclosure, the laser beam applied to the pipeline 108walls can remove a number of different unwanted deposits including, butnot limited to, scales, paraffin wax, gas hydrates, asphaltine, debris,sand or other mechanical blockages.

In one embodiment the laser radiation is used to remove the scale byvaporization. Specifically, a pulsed laser is used to produceelectromagnetic radiations having a short pulse width, high pulserepetition rate and a high average power to descale the pipeline byvaporizing molecular layers of the scale with each pulse. The amount ofscale removed is controlled by the dwell time of the beam at eachlocation which is a function of the pulse repetition rate and the speedat which the laser head is moved through the pipe. In anotherembodiment, the laser beam may remove the deposits on the pipeline 108wall through laser spallation. A high energy pulsed laser is used tocreate a compressive stress pulse in the deposit layer thereby peelingthe deposits off the pipeline 108 wall. The laser spallation process iswell known to those of ordinary skill in the art and will not bediscussed in detail herein. In other embodiments, the bursts of energydelivered to the pipeline 108 wall by the laser beam will melt anyhydrates or paraffin wax deposits on the pipeline 108 wall.

In one embodiment the laser head 104 is placed in a carrier vehicle 110which is used to transfer the laser head 104 to different locations inthe pipeline 108. In an exemplary embodiment, the carrier vehicle 110may be a pipeline tractor. The carrier vehicle 110 can move to differentpositions within the pipeline 108 while pulling the optical fiber 106along, thereby maintaining the optical communication between the lasersource 102 and the laser head 104. The carrier vehicle 110 may be placedat a particular position in the pipeline 108 or pass through all or aportion of the pipeline 108 along the pipeline axis. Additionally, thespeed of the carrier vehicle 110 may be adjusted depending on factorssuch as the pulse strength of the laser beam and the amount of deposit112 present in the pipeline 108. For example, when cleaning a section ofthe pipeline 108 wall having a thick deposit 112, the operator may slowdown the movement of the carrier vehicle 110 in order to increase theamount of time that portion of the pipeline 108 is subjected to thelaser beam.

As would be appreciated by those of ordinary skill in the art, with thebenefit of this disclosure, the laser head 104 need not be placed in acarrier vehicle and may be moved through the pipeline using a number ofdifferent mechanisms, including, but not limited to: (1) pushing thelaser head with a self motored pigging device, hydraulically drivenpigging device, coiled tubing, or jointed pipe; (2) allowing gravity tomove the laser head through the pipeline; or (3) pulling the laser headthrough the pipeline using a wire or cable.

In one embodiment, a liquid may be placed in the pipe to be cleaned andthe heat delivered from a heat source may be used to heat the liquid.The heated liquid will then remove the deposits from the pipe. In oneembodiment the heat source may be a laser head and the laser beam whichis emitted from the laser head may be used to heat the liquid.Additionally, as would be appreciated by those of ordinary skill in theart, with the benefit of this disclosure, an electrical heater or amicrowave heater may be used as the heat source in this embodiment withthe operator selecting the type of heat source to be used based onfactors such as the amount of heat required to remove the materialforming the blockage. In instances when an electrical or microwaveheater is utilized, the heat generating unit may be within the pipelineto be cleaned. The power supplied to the electrical or microwave heateris then applied to the liquid.

As would be appreciated by those of ordinary skill in the art, with thebenefit of this disclosure, a number of different liquids or mixtures ofliquids may be used depending on the material to be removed from thepipe wall and other surrounding circumstances. For instance, in oneembodiment, water may be used when the material to be removed comprisesgas hydrates. In another embodiment, where the material to be removedcomprises paraffin, a mixture of water, surfactant solutions, and othersuitable chemicals may be used.

In one exemplary embodiment, the carrier vehicle 110 is equipped with afeedback mechanism (not shown) to monitor the power incident on thepipeline 108 wall and adjust the frequency, pulse width and otherproperties of the laser at the laser source 102 to optimize the powerincident on the pipeline 108 walls. In another embodiment the feedbackmechanism is operable to perform a profilometric analysis of pipeline108 wall surfaces and deposits thereon. The performance of profilometricanalysis is known to those of ordinary skill in the art and will not bediscussed in detail herein. As would be appreciated by those of ordinaryskill in the art, with the benefit of this disclosure, the operator mayuse the information obtained from the feedback mechanism to modify theperformance of the laser head or identify cracks or other deformities inthe pipeline 108 walls.

In another exemplary embodiment, the carrier vehicle 110 is equippedwith a monitoring device (not shown) to track the progress of thecleaning device 100. In one embodiment, the monitoring device recordsthe reflectance from the pipeline 108 wall as a measure of scaleremoval. As would be appreciated by those of ordinary skill in the art,with the benefit of this disclosure, due to its luster, pure metal has ahigher level of reflectance than scales. As a result, the amount ofdeposits 112 removed can be tracked by monitoring the reflectance fromthe pipeline 108 wall with an increased reflectance indicating areduction in the amount of deposits 112 remaining.

In one exemplary embodiment the carrier vehicle 110 may be equipped toconduct a spectroscopic analysis of effluent gasses and the materialsdeposited on the pipeline 108 walls. As would be appreciated by those ofordinary skill in the art, with the benefit of this disclosure, in orderto conduct spectroscopy of the substances deposited on the pipeline 108walls, electromagnetic radiations are applied and the reflectance orabsorbance of the radiations is analyzed to determine the properties ofthe deposits. Details of conducting spectroscopy analysis on a substanceare known to those of ordinary skill in the art and are not discussed indetail herein.

In one exemplary embodiment, the carrier vehicle 110 is equipped withlenses and other appropriate beam shaping optics that may be used toadjust the properties of the laser beam directed onto the pipeline 108wall. For instance, in one embodiment, the radiation beam is passedthrough a series of aligned optical elements such as cylindrical lenses,mirrors or a combination thereof to focus the beam at a desiredlocation. In another embodiment, the radiation beam may first behomogenized to form a beam having a uniform intensity.

As would be appreciated by those of ordinary skill in the art, with thebenefit of this disclosure, although the additional equipment isdescribed as being coupled to the carrier vehicle 110, these equipmentneed not be placed directly on the carrier vehicle and can be otherwisecoupled thereto or may be capable of independent navigation through thepipeline. Moreover, as would be appreciated by those of ordinary skillin the art, with the benefit of this disclosure, some of the equipmentused in analysis of the conditions inside the pipeline may be placedoutside the pipeline and may be communicatively coupled to the equipmentinside the pipeline through the optical fibers.

Additionally, in certain exemplary embodiments, the carrier vehicle 110may be equipped with a pigging mechanism or mechanical scrapper whichcan assist in removal of the cracked or broken deposits as they areseparated from the pipeline 108 wall.

In one exemplary embodiment the laser assisted cleaning apparatus 100may be utilized to remove a complete blockage in the pipeline. In oneembodiment, the unit may first inspect the form and orientation of theblockage at hand. As would be appreciated by those of ordinary skill inthe art, with the benefit of this disclosure, a variety of differentmechanisms may be used to inspect the blockage. In one embodiment, theinspection may be through the use of video technology, proximity sensorsor other non mechanical/tactile sensory devices. A detailed discussionof the operation of such inspection devices is not included herein as itis known to those of ordinary skill in the art. After inspection, thelaser head 104 will deliver the laser beam supplied by the laser source102 to the blockage. In one embodiment, the laser beam would be used toestablish a flow path through the blockage in order to allow the use ofmore traditional deposit removal systems such as treatment chemicals.Alternatively, the laser beam may be used to completely remove theblockage and deposits adhered to the walls of the pipeline 108, therebyclearing the blockage.

In another Exemplary embodiment, the laser assisted cleaning apparatus100 may be adjusted to provide sufficient power to cut a window in thepipe walls at a desired location. In this embodiment, the carriervehicle 110 is moved through the pipeline and placed in a location wherea window is desired through the pipeline 108. The power delivered by thelaser source 102 is adjusted such that the laser head 104 can deliversufficient power to the pipeline 108 wall to create a window in thepipeline 108.

As would be appreciated by those of ordinary skill in the art, with thebenefit of this disclosure, the laser assisted cleaning apparatus 100 ofthe present invention may be used independently, or in conjunction withother current methods of cleaning deposits in pipelines. For example, ininstances of pipeline blockage when the passage of deposit removingfluids through the pipeline proves ineffective, the laser assistedcleaning apparatus 100 of the present invention can be used to apply alaser beam to the materials forming the blockage. The application of thelaser beam will remove the blockage providing a path for fluids to flow.The creation of a path for fluid flow permits the use of moretraditional deposit removal methods such as the use of treatmentchemicals.

In one exemplary embodiment the pipeline to be cleaned may be subjectedto de-oiling before the pipeline is cleaned by the laser beam. In thisexemplary embodiment, a plug of surfactant solutions can be sent aheadof the laser head to clean the pipeline surface before it is subjectedto the laser beam in order to prevent an ignition resulting from theincident laser beam.

Although the present invention is described in the context of oil fieldapplications, as would be appreciated by those of ordinary skill in theart, with the benefit of this disclosure, the present invention may beused for cleaning any conduit that is used for transfer of fluids. Forexample, the present invention may be used to clean water pipes thathave become partially or fully blocked due to water impurities or thelike.

Additionally, although the present invention is described in the contextof oil pipelines, as would be appreciated by those of ordinary skill inthe art, methods and apparatuses in accordance with an embodiment of thepresent invention may be used in conjunction with any hydrocarbontransfer conduits above the grounds or down hole, such as, for example,in well bores.

Hence, the laser assisted cleaning apparatus of the present invention iscapable of operating with great precision, simulating an optical chisel,thereby eliminating the need for using large volumes of hazardouschemicals. Moreover, considering the availability of high power lasersources, the power supplied by the laser source 102 can be increased toefficiently remove hard scales such as barium sulfate. Additionally, thelaser assisted cleaning apparatus of the present invention may beequipped with feedback mechanisms and the necessary equipment to analyzethe conditions in a pipeline.

Therefore, the present invention is well adapted to attain the ends andadvantages mentioned as well as those that are inherent therein. Theparticular embodiments disclosed above are illustrative only, as thepresent invention may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Furthermore, no limitations areintended to the details of construction or design herein shown, otherthan as described in the claims below. It is therefore evident that theparticular illustrative embodiments disclosed above may be altered ormodified and all such variations are considered within the scope andspirit of the present invention. Also, the terms in the claims havetheir plain and ordinary meaning unless otherwise explicitly and clearlydefined by the patentee.

1. A method of removing deposits from a hydrocarbon transfer conduit comprising the steps of: placing a laser head in a hydrocarbon transfer conduit to be cleaned; supplying the laser head with a laser beam; and, applying the laser beam from the laser head to an area in the hydrocarbon transfer conduit to be cleaned.
 2. The method of claim 1, wherein the laser beam is supplied to the laser head from a laser source.
 3. The method of claim 2, wherein the laser source is optically coupled to the laser head.
 4. The method of claim 2, wherein the laser source is placed outside the hydrocarbon transfer conduit.
 5. The method of claim 1, wherein the laser head is placed in a carrier vehicle.
 6. The method of claim 5, wherein the carrier vehicle operates to transport the laser head in the hydrocarbon transfer conduit.
 7. The method of claim 1, wherein the area in the hydrocarbon transfer conduit to be cleaned is a hydrocarbon transfer conduit wall or a portion of a cross section of a hydrocarbon transfer conduit.
 8. The method of claim 1, wherein the laser head is operable to direct a laser beam to one of a wall of the hydrocarbon transfer conduit to be cleaned or a portion of a cross section of the hydrocarbon transfer conduit to be cleaned.
 9. The method of claim 1, further comprising the step of inspecting a deposit formation in the hydrocarbon transfer conduit before applying the laser beam from the laser head to the area in the hydrocarbon transfer conduit to be cleaned.
 10. The method of claim 9, wherein inspecting the deposit formation is conducted using one of a proximity sensor or a video system.
 11. The method of claim 1, further comprising conducting a spectroscopic analysis of one of an effluent gas or a deposit formation in the hydrocarbon transfer conduit.
 12. The method of claim 1, further comprising conducting a profilometric analysis of a hydrocarbon transfer conduit wall surface.
 13. The method of claim 1, wherein a deposit to be removed from the hydrocarbon transfer conduit is a scale, a paraffin, an asphaltine, a gas hydrate or sand.
 14. A method of removing deposits from a pipe comprising the steps of: placing a heat source in a pipe to be cleaned; placing a liquid in the pipe to be cleaned; supplying the heat source with power; and, applying the power from the heat source to the liquid in an area in the pipe to be cleaned.
 15. The method of claim 14, wherein the heat source is a laser head, an electrical heater or a microwave heater.
 16. The method of claim 15, wherein a laser source supplies the laser head with a laser beam.
 17. The method of claim 16, wherein the laser source is placed outside the pipe to be cleaned.
 18. The method of claim 16, wherein the laser head and the laser source are communicatively coupled with an optical fiber.
 19. The method of claim 16, wherein the laser source is adjustable to provide a laser beam having at least one of a desirable frequency, a desirable amplitude and a desirable power.
 20. The method of claim 14, wherein the heat source is coupled to a carrier vehicle.
 21. The method of claim 20, wherein a speed of the carrier vehicle is adjustable.
 22. The method of claim 14, further comprising the step of monitoring deposit removal with a feedback mechanism.
 23. The method of claim 22, wherein the feedback mechanism comprises one of a reflectance sensor, an optical sensor, a temperature sensor, or a video system.
 24. A hydrocarbon transfer conduit cleaning apparatus comprising: a laser head; a laser source; and, an optical fiber communicatively coupling the laser head and the laser source; wherein the laser head is placed in a hydrocarbon transfer conduit to be cleaned.
 25. The apparatus of claim 24, wherein a power supplied by the laser head to the hydrocarbon transfer conduit can be sufficiently increased to cut a window in a hydrocarbon transfer conduit wall. 